Refrigeration device

ABSTRACT

This refrigeration device is provided with: an evaporator configuring a refrigeration circuit; a cascade condenser configuring the refrigeration circuit; and a thermal insulation board arranged between the evaporator and the cascade condenser.

CROSS-REFERENCE OF RELATED APPLICATIONS

This application is the U.S. Continuation of International PatentApplication No. PCT/JP2018/017861, filed on May 9, 2018, which in turnclaims the benefit of Japanese Application No. 2017-101960, filed on May23, 2017, the entire disclosures of which Applications are incorporatedby reference herein.

TECHNICAL FIELD

The present invention relates to a refrigeration apparatus.

BACKGROUND ART

Conventionally, a cascade refrigeration apparatus is used as arefrigeration apparatus such as an ultra-low temperature freezer whosein-compartment temperature reaches, for example, −85° C. The cascaderefrigeration apparatus includes a high-temperature side refrigerationcircuit, a low-temperature side refrigeration circuit, and a heatexchanger configured to exchange heat between refrigerants that flowthrough these refrigeration circuits. As a refrigeration apparatus suchas an ultra-low temperature freezer, another refrigeration apparatus isused which includes a heat exchanger configured to exchange heat betweena low-temperature refrigerant and a gas-side refrigerant, thelow-temperature refrigerant being obtained by liquid-gas separating arefrigerant in a refrigeration circuit and expanding a liquid-siderefrigerant. These heat exchangers are called a cascade condenser.

In these cascade refrigerators, a refrigerant circulating through ahigh-temperature-side refrigeration circuit (hereinafter, referred to asa “high-temperature-side refrigerant”) evaporates at the cascadecondenser, and heat is removed from a refrigerant circulating through alow-temperature-side refrigeration circuit (hereinafter, referred to asa “low-temperature-side refrigerant”) at the cascade condenser. At thistime, the low-temperature-side refrigerant is condensed and liquefied.Additionally, the low-temperature-side refrigerant evaporates within anevaporator that makes up the low-temperature-side refrigeration circuitto thereby cool an interior of a refrigeration compartment situatedadjacent to the evaporator.

One cascade refrigeration apparatus is disclosed in PTL 1. This cascaderefrigeration apparatus includes a heat insulation box body packed witha foamed heat insulating material. An intermediate heat exchanger (acascade condenser) is provided inside the heat insulation box body. Arefrigeration compartment is disposed on the heat insulation box body,and a first evaporator (an evaporator) is disposed on a back surface ofthe refrigeration compartment.

CITATION LIST Patent Literature

-   PTL 1-   Japanese Patent Application Laid-Open No. 2012-7781

SUMMARY OF INVENTION Technical Problem

Although the cascade refrigeration apparatus described in PTL 1 has theconfiguration described above, heat insulation between the cascadecondenser and the evaporator is effected by part of the foamed heatinsulating material packed in the heat insulating box body, asillustrated in FIG. 1 of PTL 1. The study carried out by the inventorand others makes it clear that this heat insulation structure involvesthe following problems.

That is, it has been found out that the heat insulating material cannotbe packed sufficiently between an inner box that makes up the heatinsulation box body and the cascade condenser, generating a non-packedportion where the heat insulating material is not packed and/or aninsufficiently packed portion where the heat insulating material isinsufficient and is packed thin in that portion from time to time.

In such a state, a heat transmission is caused between the cascadecondenser which is supplied with the low-temperature-side refrigerantdischarged from the compressor and heated to a high temperature and theevaporator which is supplied with the low-temperature-side refrigerantpassed through a throttle expansion device such as an expansion valveand cooled to a low temperature. When such a heat transmission iscaused, the performance of the cascade refrigeration apparatus isreduced.

Such a reduction in performance due to the occurrence of a heattransmission between a cascade condenser and an evaporator is notlimited to a cascade refrigeration apparatus but is a common problem torefrigeration apparatuses including a cascade condenser.

An object of the present invention, which has been made in view of thesesituations, is to provide a refrigeration apparatus which can reduce aheat transmission between a cascade condenser and an evaporator.

Solution to Problem

A refrigeration apparatus according to the present invention includes:an evaporator that makes up a refrigeration circuit; a cascade condenserthat makes up the refrigeration circuit; and a heat insulating boarddisposed between the evaporator and the cascade condenser.

Advantageous Effects of Invention

According to the present invention, the refrigeration apparatus can beprovided in which the heat transmission between the cascade condenserand the evaporator can be reduced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a rear view of a refrigeration apparatus according toEmbodiment 1;

FIG. 2 is a circuit diagram illustrating refrigeration circuits andconstituent devices thereof;

FIG. 3 is a cross-sectional view taken along line III-III and viewed ina direction indicated by arrows III of FIG. 1;

FIG. 4 is a perspective view of an inner box and an evaporator;

FIG. 5 is a horizontal cross-sectional view of a reference example;

FIG. 6A is a schematic view of a periphery of a cascade condenserdisposition portion of the reference example;

FIG. 6B is a schematic view of the periphery of the cascade condenserdisposition portion of the reference example after deformation;

FIG. 6C is a schematic view of a periphery of a cascade condenserdisposition portion of the refrigeration apparatus according to thefirst embodiment;

FIG. 7 is a horizontal cross-sectional view of a refrigeration apparatusaccording to Embodiment 2;

FIG. 8 is a horizontal cross-sectional view of a refrigeration apparatusaccording to Embodiment 3;

FIG. 9 is an internal structural view of a refrigeration apparatusaccording to Embodiment 4; and

FIG. 10 is a perspective view of an insulating board of a modifiedexample.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described in detail withreference to accompanying drawings. The following embodiments areexamples, and the present invention is not limited by these embodimentsin any way.

Embodiment 1

FIG. 1 is a rear view of a refrigeration apparatus according toEmbodiment 1. Refrigeration apparatus 1 includes machine installingsection 2 and main body 3 provided thereon.

Various devices and a control section that make up refrigeration circuit60 (refer to FIG. 2) are disposed in an interior of machine installingsection 2. Refrigeration circuit 60 and the various devices that make uprefrigeration circuit 60 will be described in detail later.

On a rear surface of main body 3, cascade condenser disposition section39 (to be described later) where first cascade condenser 616 (to bedescribed later), second cascade condenser 626 (to be described later),and the like are disposed is provided, and lid 31 configured to closecascade condenser disposition section 39 is attached.

FIG. 2 is a cycle diagram illustrating main constituent devices thatmakes up refrigeration circuit 60. Refrigeration circuit 60 includesfirst refrigeration circuit 610 and second refrigeration circuit 620 inwhich refrigerants circulate independently of each other. Firstrefrigeration circuit 610 and second refrigeration circuit 620 can bothbe operated simultaneously. Alternatively, only either of firstrefrigeration circuit 610 and second refrigeration circuit 620 can alsobe operated for the sake of energy conservation or service maintenanceof the other.

First refrigeration circuit 610 includes first compressor 611, firstpre-condenser 612 and first condenser 613, first separator 614configured to separate a refrigerant into gas and liquid, firstauxiliary decompression device 615 and first cascade condenser 616, andfirst decompression device 617 and first evaporator pipe 618. Theseconstituent devices are connected together with a predetermined piping(a first piping) so that a refrigerant (a first refrigerant) dischargedfrom first compressor 611 returns to first compressor 611. For example,a non-azeotropic mixture refrigerant containing four differentrefrigerants (hereinafter, referred to simply as a “refrigerant”) issealed in first refrigeration circuit 610.

First refrigeration circuit 610 includes first oil cooler 611 a in anoil reservoir in first compressor 611 and includes first annular piping611 b between first pre-condenser 612 and first oil cooler 611 a.

First compressor 611 compresses a sucked refrigerant and discharges therefrigerant to first pre-condenser 612.

First pre-condenser 612 is made up, for example, of a serpentine copperor aluminum pipe configured to dissipate heat from the refrigerantdischarged from first compressor 611.

First condenser 613 is made up, for example, of a serpentine copper oraluminum pipe configured to dissipate heat further from the refrigerantoutputted from first pre-condenser 612.

First pre-condenser 612 and first condenser 613 are integrated into, forexample, a single pipe plate. First common fan 619 is disposed nearfirst pre-condenser 612 and first condenser 613 to blow air againstfirst pre-condenser 612 and first condenser 613 simultaneously.

First separator 614 separates the refrigerant outputted from firstcondenser 613 into a liquid-phase refrigerant and a gas-phaserefrigerant. After having been so separated, the liquid-phaserefrigerant is decompressed in first auxiliary decompression device 615(for example, a capillary tube), whereafter the decompressed refrigerantevaporates in first outer pipe 616 a of first cascade condenser 616.

First cascade condenser 616 is made up, for example, of a copper oraluminum duplex pipe including first outer pipe 616 a and first innerpipe 616 b. The gas-phase refrigerant from first separator 614 flowsinto first inner pipe 616 b. In first outer pipe 616 a, the liquid-phaserefrigerant evaporates to cool the gas-phase refrigerant flowing throughfirst inner pipe 616 b.

First decompression device 617 (for example, a capillary tube)decompresses a refrigerant that is cooled in first inner pipe 616 b offirst cascade condenser 616 to be in a liquid phase and outputs thedecompressed refrigerant to first evaporator pipe 618.

First evaporator pipe 618 is made up, for example, of a copper oraluminum pipe configured to evaporate the refrigerant decompressed infirst decompression device 617 and is thermally affixed to an outersurface of inner box 35 (refer to FIG. 3) that makes up main body 3excluding an opening thereof in such a manner as to be in contact withthe outer surface. First evaporator pipe 618 makes up evaporator pipe 38together with second evaporator pipe 628, which will be described later.

An interior of inner box 35 is cooled by a cooling effect produced whenthe refrigerant evaporates (vaporizes) in first evaporator pipe 618. Therefrigerant that evaporates in first evaporator pipe 618 to be in agas-phase merges with the refrigerant that has evaporated beforehand infirst cascade condenser 616, and both the refrigerants are sucked intofirst compressor 611.

Second refrigeration circuit 620 has a similar configuration to that offirst refrigeration circuit 610. That is, second refrigeration circuit620 includes second compressor 621, second pre-condenser 622 and secondcondenser 623, second separator 624 configured to separate a refrigerantinto liquid and gas, second auxiliary decompression device 625 andsecond cascade condenser 626, and second decompression device 627 andsecond evaporator pipe 628. Constituent devices are connected togetherby a predetermined piping (a second piping) in such a manner that arefrigerant (a second refrigerant) discharged from second compressor 621returns to second compressor 621 again. A similar refrigerant to therefrigerant used in first refrigeration circuit 610 is also used insecond refrigeration circuit 620.

Similar to first refrigeration circuit 610, second refrigeration circuit620 includes second oil cooler 621 a, and a second annular piping 621 b.Second cascade condenser 626 includes second outer pipe 626 a and secondinner pipe 626 b.

Second pre-condenser 622 and second condenser 623 are integrated into,for example, a single pipe plate. Second common fan 629 is disposed nearsecond pre-condenser 622 and second condenser 623 to blow air againstsecond pre-condenser 622 and second condenser 623 simultaneously.

First annular piping 611 b and second annular piping 621 b are providedon a circumference of the opening in main body 3. This circumferentialportion of the opening constitutes a portion where condensation orfrosting tends to be generated easily. However, since a refrigerant of arelatively high temperature flows through first annular piping 611 b andsecond annular piping 621 b, the circumferential portion of the openingin main body 3 can be heated, thereby making it possible to prevent theoccurrence of condensation or frosting.

In refrigeration apparatus 1 configured as has been describedheretofore, cooling compartment 32 (which will be described later) iscooled by first refrigeration circuit 610 and/or second refrigerationcircuit 620, or specifically the refrigerants flowing in the interiorsof first evaporator pipe 618 and second evaporator pipe 628 or therefrigerant flowing in the interior of first evaporator pipe 618 orsecond evaporator pipe 628.

FIG. 3 illustrates a cross-sectional view taken along line III-III andviewed in a direction indicated by arrows III in FIG. 1. Main body 3includes inner box 35 made up of an iron plate and opened at a frontthereof, outer box 36 made up of an iron plate and opened at a frontthereof, and heat insulating material 37 packed in a space definedbetween inner box 35 and outer box 36. Heat insulating material 37 isformed from a spongy resin that is supplied in the form of mousse-likeliquid and is then solidified to have a number of independent cells, forexample, foamed urethane. Cooling compartment 32 where cooling targetarticles are installed is formed in an interior of inner box 35. Door 34is attached to outer box 36 via hinges 33 (refer to FIG. 1) in such amanner as to be opened and closed. Door 34 is a plate-like member of astructure in which an arbitrary heat insulating member is surrounded byan iron plate. First annular piping 611 b and second annular piping 621b are not illustrated in the figure.

FIG. 4 is a perspective view of inner box 35 as viewed from a rear andbelow. As illustrated in FIG. 4, first evaporator pipe 618 and secondevaporator pipe 628, which make up evaporator pipe 38, are laid out onan outer surface of inner box 35 in such a manner as to surround innerbox 35, that is, cooling compartment 32 illustrated in FIG. 3. Firstevaporator pipe 618 and second evaporator pipe 628 individually includea plurality of straight pipe sections 383.

First evaporator pipe 618 and second evaporator pipe 628 are providedalong the outer surface, specifically, lower surface 351, right surface352, rear surface 353, a left surface (not shown), and an upper surface(not shown) of inner box 35 in such a manner as to be in contacttherewith. First evaporator pipe 618 and second evaporator pipe 628 areattached to the outer surface of inner box 35 with, for example, a metaltape (not shown)of aluminum or the like on one side of which an adhesionlayer is provided. First evaporator pipe 618 includes first evaporatorpipe inlet 618 a and first evaporator pipe outlet 618 b. Secondevaporator pipe 628 includes a second evaporator pipe inlet 628 a andsecond evaporator pipe outlet 628 b.

FIG. 3 is referred to again. As illustrated in FIG. 3, cascade condenserdisposition section 39 is provided on the rear surface of main body 3.Cascade condenser disposition section 39 is provided in a position atouter side of inner box 35 and an inner side of outer box 36. Cascadecondenser disposition section 39 is surrounded on upper, lower, left,and right sides thereof with heat insulating material 37 packed betweeninner box 35 and outer box 36.

Cascade condenser disposition section 39 includes a resting section (notshown) where first cascade condenser 616 and second cascade condenser626 are rested. First evaporator pipe inlet 618 a, first evaporator pipeoutlet 618 b, second evaporator pipe inlet 628 a, and second evaporatorpipe outlet 628 b are disposed in cascade condenser disposition section39. Additionally, first decompression device 617 and seconddecompression device 627 are disposed in cascade condenser dispositionsection 39. First evaporator pipe inlet 618 a is connected to firstcascade condenser 616 (first inner pipe 616 b) via first decompressiondevice 617. First evaporator pipe outlet 618 b is connected to firstcompressor 611 via first cascade condenser 616 (first outer pipe 616 a).Second evaporator pipe inlet 628 a is connected to second cascadecondenser 626 (second inner pipe 626 b) via second decompression device627. Second evaporator pipe outlet 628 b is connected to secondcompressor 621 via second cascade condenser 626 (second outer pipe 626a).

In refrigeration apparatus 1 according to this embodiment, hole 361 isprovided in outer box 36. A position where hole 361 is provided matchesa rear surface side of cascade condenser disposition section 39.

Part of evaporator pipe 38, heat insulating board 51, first cascadecondenser 616 and second cascade condenser 626 are disposed sequentiallyfrom an inner box 35 side to an outer box 36 side in cascade condenserdisposition section 39. Heat insulating board 51 is fixed to rearsurface 353 of inner box 35 with, for example, an adhesive tape (notshown). First cascade condenser 616 and second cascade condenser 626 aredisposed to be aligned side by side. Cascade condenser dispositionsection 39 is closed with lid 31 after the devices are installed incascade condenser disposition section 39. Lid 31 is detachably attachedto outer box 36 with bolts, not shown, or the like and is detached fromouter box 36 for service maintenance of first cascade condenser 616 orsecond cascade condenser 626. Lid 31 is a plate-like member having astructure in which an arbitrary heat insulating member is surrounded byan iron plate.

Heat insulating board 51 is a resin plate member formed in advance usinga known method in a factory or the like and having a number ofindependent cells in an interior thereof and is formed of, for example,a hard polyurethane. Heat insulating board 51 may be formed of anymaterial, as long as the material has sufficient heat insulatingproperties and rigidity enabling heat insulating board 51 to maintainits plate-like shape and may be, for example, a so-called vacuum heatinsulating material that is a member containing glass fibers as a corematerial or member in which a vacuum heat insulating material and aplate member having sufficient rigidity are laminated on each other.

Heat insulating board 51 is sized and shaped so that first cascadecondenser 616 and second cascade condenser 626 are hidden behind heatinsulating board 51 to become invisible when heat insulating board 51,first cascade condenser 616, and second cascade condenser 626 aredisposed in cascade condenser disposition section 39 and these devicesare seen from a front side of refrigeration apparatus 1. Thus, heatinsulating board 51 is interposed between first and second cascadecondensers 616, 626 and evaporator pipe 38 to interrupt heattransmission therebetween, thereby making it possible to reduce the heattransmission in an ensured fashion.

Heat insulating board 51 preferably has a thickness of 10 mm to 20 mm.Having the thickness of 10 mm or greater, heat insulating board 51 canobtain sufficiently great heat insulating properties and mechanicalstrength (rigidity). Heat insulating board 51 having the thickness of 20mm or smaller, a ratio of a space in a thickness direction to a space(cascade condenser disposition section 39) defined between inner box 35and outer box 36 can be reduced to a relatively small level, whereby aspace where to install first cascade condenser 616 and second cascadecondenser 626 can be secured sufficiently. In the case where the vacuumheat insulating material is used, with a thickness of the order of 1 mm,sufficient heat insulating properties can be obtained.

Heat insulating board 51 has preferably a heat transmissivity of 0.050W/(m·K) or smaller, more preferably a heat transmissivity of 0.030W/(m·K) or smaller, and much more preferably a heat transmissivity of0.024 W/(m·K) or smaller to obtain a sufficient heat insulatingperformance.

Heat insulating material 37 is preferably packed after inner box 35where evaporator pipe 38 is mounted and outer box 36 are disposed insuch a manner as to define a space therebetween and heat insulatingboard 51 is disposed on a side of evaporator pipe 38 which faces outerbox 36. As a result, heat insulating material 37 can be packed fully inspaces on upper, lower, left, and right sides of heat insulating board51 without any gap left, whereby the heat insulating properties aroundcascade condenser disposition section 39 can be enhanced.

In refrigeration apparatus 1 according to the embodiment that isconfigured as has been described heretofore, the refrigerants inrefrigeration circuit 60 evaporate in evaporator pipe 38, whereby anultra-low temperature is provided on the circumference of evaporatorpipe 38. Thus, cooling compartment 32 surrounded by evaporator pipe 38can be cooled down via inner box 35 to a low temperature. The heattransmission between first and second cascade condensers 616, 626 andevaporator pipe 38 is interrupted by heat insulating board 51.Consequently, the performance of refrigeration apparatus 1 can beincreased.

Here, the function and advantageous effect of refrigeration apparatus 1according to this embodiment will be described in greater detail bycomparing with a refrigeration apparatus of a reference example.

FIG. 5 is a horizontal cross-sectional view of a refrigeration apparatus1 of a reference example. In refrigeration apparatus 1 according to thereference example, spongy heat insulating material 37, which is suppliedin the form of mousse-like liquid and is then solidified to have anumber of independent cells, is packed between first and second cascadecondensers 616, 626 and evaporator pipe 38. Heat insulating material 37is packed in such a state that film sheet 71 and jig 72 having shapematching cascade condenser disposition section 39 and disposed incascade condenser disposition section 39 only when heat insulatingmaterial 37 is packed are disposed in cascade condenser dispositionsection 39, as illustrated in FIG. 5. FIG. 4 is a diagram illustrating astate resulting in the midst of fabrication of refrigeration apparatus 1according to the reference example, and hence, first cascade condenser616 and second cascade condenser 626 are not illustrated. These twocascade condensers are disposed in cascade condenser disposition section39 as done in the embodiment illustrated in FIG. 3 after jig 72 isremoved.

In refrigeration apparatus 1 according to the reference example,although a sufficient amount of heat insulating material 37 is desirablypacked between film sheet 71 and evaporator pipe 38 at the time offabrication, a space between jig 72 and evaporator pipe 38 and inner box35 is narrow. In addition, in refrigeration apparatus 1 according to thereference example, an area of the portion between jig 72 and evaporatorpipe 38 and inner box 35 is increased (in other words, a distance overwhich heat insulating material 37 penetrates is long). Due to this, asillustrated in FIG. 5, a drawback such as non-packed portion 371 whereno heat insulating material 37 exists or insufficiently packed portion372 where heat insulating material 37 is laid out thin is generatedbetween first and second cascade condensers 616, 626 (both not shown)and evaporator pipe 38 due to variation in packing. Consequently, inrefrigeration apparatus 1 according the reference example, the heattransmission between first and second cascade condensers 616, 626 andevaporator pipe 38 cannot be reduced sufficiently.

On the contrary to this, in refrigeration apparatus 1 according to thisembodiment, heat insulating board 51 having neither a through hole nor athin portion is disposed between first and second cascade condensers616, 626 and evaporator pipe 38. Consequently, the heat transmissionbetween first and second cascade condensers 616, 626 and evaporator pipe38 can be reduced effectively. According to refrigeration apparatus 1according to this embodiment, irrespective of the size of cascadecondenser disposition section 39, that is, the number of cascadecondensers disposed or size thereof, or without any possibility of apacking failure in insufficiently packed heat insulating material 37,the heat transmission reduction effect can be obtained.

FIG. 6A is a cross-sectional view taken along line VIa-VIa and viewed ina direction indicated by arrows VIa in FIG. 5, illustrating acircumference of cascade condenser disposition section 39. Asillustrated in FIG. 6A, in refrigeration apparatus 1 according to thereference example, non-packed portion 371 and insufficiently packedportion 372 exist. Due to this, in the case where during transportation,fabrication or the like, vibrations or impact is applied torefrigeration apparatus 1, and forces indicated by arrows in FIG. 6A areapplied to heat insulating material 37 surrounding cascade condenserdisposition section 39, heat insulating material 37 is deformed,resulting in possibilities that crack 373 is generated as illustrated inFIG. 6B. Since the heat insulating performance of heat insulatingmaterial 37 is reduced by crack 373 so generated, whereby theperformance of refrigeration apparatus 1 is further reduced.Additionally, since evaporator pipe 38 that is cooled to a lowtemperature and an outer side of heat insulating material 37 are causedto communicate with each other via crack 373, a risk of condensationbeing generated on the circumference of evaporator pipe 38 is increased.Condensed water may trigger corrosion of circumferential metallicmembers or hydrolyzing of resin members.

On the contrary to this, in refrigeration apparatus 1 of thisembodiment, heat insulating board 51 is interposed between first andsecond cascade condensers 616, 626 and evaporator pipe 38. Heatinsulating board 51 has neither a through hole nor a thin portion andhas high rigidity. Moreover, as illustrated in FIG. 6C which is across-sectional view taken along VIc-VIc and viewed in a directionindicated by arrows VIc in FIG. 3 (a periphery of cascade condenserdisposition portion 39), packed heat insulating material 37 and heatinsulating board 51 are closely secured to each other, generating no gaptherebetween. Thus, even though vibration or impact is applied torefrigeration apparatus 1 during transportation, fabrication or the likeand forces indicated by arrows in FIG. 6C are applied to heat insulatingmaterial 37 surrounding cascade condenser disposition section 39, thereare no possibilities that heat insulating material 37 is deformed to becracked. That is, the mechanical strength of heat insulating material 37can be enhanced by heat insulating board 51. Hence, a reduction inperformance of refrigeration apparatus 1 or deterioration in theconstituent members that is attributed to cracking of heat insulatingmaterial 37 can be prevented in an ensured fashion.

In refrigeration apparatus 1 according to this embodiment, needless tosay, the numbers of refrigeration circuits 60 and cascade condensersthat makes up refrigeration circuit 60 are not limited to two, andhence, the numbers of refrigeration circuits 60 and cascade condensersthat makes up refrigeration circuit 60 may be one or three or greater.

Embodiment 2

Next, referring to FIG. 7, Embodiment 2 will be described mainly onfeatures different from Embodiment 1. FIG. 7 is a horizontalcross-sectional view of refrigeration apparatus 1 according to thisembodiment. First cascade condenser 616 and second cascade condenser626, which make up refrigeration apparatus 1 of this embodiment, need noservice maintenance after fabrication. Due to this, outer box 36 has nohole 361 (refer to FIG. 2). Consequently, refrigeration apparatus 1according to this embodiment does not have lid 31 that refrigerationapparatus 1 of Embodiment 1 has.

To prevent a heat transmission between first cascade condenser 616 andsecond cascade condenser 626 and outside air and, hence, a reduction inperformance of refrigeration apparatus 1, a heat insulating body in acertain form needs to be disposed between these cascade condensers andouter box 36.

Then, in this embodiment, as illustrated in FIG. 7, second heatinsulating board 52 is disposed between first and second cascadecondensers 616, 626 and outer box 36. Thus, sufficient heat insulatingproperties can be obtained while relatively reducing a distance betweenfirst and second cascade condensers 616, 626 and outer box 36. Thus, adepth of refrigeration apparatus 1 can be reduced. Consequently, thedegree of freedom in placing refrigeration apparatus 1 is increased byreducing a space necessary to place refrigeration apparatus 1, andspaces necessary for transportation and storage can also be reduced.

Second heat insulating board 52 is sized and shaped so that firstcascade condenser 616 and second cascade condenser 626 are hidden behindsecond heat insulating board 52 to become invisible when second heatinsulating board 52, first cascade condenser 616, and second cascadecondenser 626 are disposed in cascade condenser disposition section 39and these devices are seen from a rear surface side of refrigerationapparatus 1. Thus, second heat insulating board 52 is interposed betweenfirst and second cascade condensers 616, 626 and outside air tointerrupt heat transmission therebetween, thereby making it possible toreduce the heat transmission in an ensured fashion.

Second heat insulating board 52 preferably has a thickness of 10 mm to20 mm. Having the thickness of 10 mm or greater, second heat insulatingboard 52 can obtain sufficiently great heat insulating properties andmechanical strength (rigidity). Second heat insulating board 52 havingthe thickness of 20 mm or smaller, a ratio of a space in a thicknessdirection to a space (cascade condenser disposition section 39) definedbetween inner box 35 and outer box 36 can be reduced to a relativelysmall level. In the case where a vacuum heat insulating material isused, with a thickness of the order of 1 mm, sufficient heat insulatingproperties can be obtained.

Second heat insulating board 52 has preferably a heat transmissivity of0.050 W/(m·K) or smaller, more preferably a heat transmissivity of 0.030W/(m·K) or smaller, and much more preferably a heat transmissivity of0.024 W/(m·K) or smaller to obtain a sufficient heat insulatingperformance.

Heat insulating material 37 is preferably packed after inner box 35where evaporator pipe 38 is mounted and outer box 36 are disposed insuch a manner as to define a space therebetween and heat insulatingboard 51, first cascade condenser 616 and second cascade condenser 626,and second heat insulating board 52 are disposed on a side of evaporatorpipe 38 which faces outer box 36. As a result, heat insulating material37 can be packed fully in spaces on upper, lower, left, and right sidesof heat insulating board 51, first cascade condenser 616 and secondcascade condenser 626, and second heat insulating board 52 without anygap left, whereby the heat insulating properties around cascadecondenser disposition section 39 can be enhanced.

In refrigeration apparatus 1 according to the embodiment that isconfigured as has been described heretofore, the refrigerants inrefrigeration circuit 60 evaporate in evaporator pipe 38, whereby anultra-low temperature is provided on the circumference of evaporatorpipe 38. Thus, an interior of cooling compartment 32 surrounded byevaporator pipe 38 via inner box 35 can be cooled down to a lowtemperature. The heat transmission between first and second cascadecondensers 616, 626 and evaporator pipe 38 is interrupted by heatinsulating board 51. Further, the heat transmission between the firstand second cascade condensers 616, 626 and outside air is interrupted bysecond heat insulating board 52. Consequently, the performance ofrefrigeration apparatus 1 can be increased.

Similar to first heat insulating board 51, second heat insulating board52 can also provide an advantageous effect of increasing the mechanicalstrength of heat insulating material 37.

Embodiment 3

Next, referring to FIG. 8, Embodiment 3 will be described mainly onfeatures different from Embodiment 1. FIG. 8 is a horizontalcross-sectional view of refrigeration apparatus 1 according to thisembodiment. In refrigeration apparatus 1 according this embodiment,first cascade condenser 616 and second cascade condenser 626 aredisposed laterally side by side within cascade condenser dispositionsection 39.

In the case where an operating condition such as an attaining targettemperature or refrigerant flow rate differs between first refrigerationcircuit 610 and second refrigeration circuit 620, a temperature of arefrigerant flowing through an interior of first cascade condenser 616and a temperature of a refrigerant flowing through an interior of secondcascade condenser 626 come to differ from each other. As this occurs,there are caused possibilities that a heat transmission is generatedbetween first cascade condenser 616 and second cascade condenser 626. Inthe event that such a heat transmission is generated, there are causedpossibilities that the performance of refrigeration apparatus 1 isreduced.

Then, in refrigerant apparatus 1 according to this embodiment, thirdheat insulating board 53 is disposed between first cascade condenser 616and second cascade condenser 626. Thus, a heat transmission betweenfirst cascade condenser 616 and second cascade condenser 626 is reduced,thereby making it possible to improve the performance of refrigerationapparatus 1.

Third heat insulating board 53 is sized and shaped so that one of firstcascade condenser 616 and second cascade condenser 626 is hidden behindthird heat insulating board 53 to become invisible when third heatinsulating board 53, first cascade condenser 616, and second cascadecondenser 626 are disposed in cascade condenser disposition section 39and these devices are seen from a lateral surface side of refrigerationapparatus 1. Thus, third heat insulating board 53 is interposed betweenfirst cascade condenser 616 and second cascade condenser 626 tointerrupt heat transmission therebetween, thereby making it possible toreduce the heat transmission in an ensured fashion.

Third heat insulating board 53 preferably has a thickness of 10 mm orgreater. Having the thickness of 10 mm or greater, third heat insulatingboard 53 can obtain sufficiently great heat insulating properties andmechanical strength (rigidity). In the case where a vacuum heatinsulating material is used, with a thickness of the order of 1 mm,sufficient heat insulating properties can be obtained.

Third heat insulating board 53 has preferably a heat transmissivity of0.050 W/(m·K) or smaller, more preferably a heat transmissivity of 0.030W/(m·K) or smaller, and much more preferably a heat transmissivity of0.024 W/(m·K) or smaller to obtain a sufficient heat insulatingperformance.

In refrigeration apparatus 1 according to this embodiment, three or morecascade condensers may be disposed. In this case, third heat insulatingboard 53 is preferably disposed in each of spaces defined between thecascade condensers. As a result, a heat transmission among the cascadecondensers can be reduced in an ensured fashion.

Embodiment 4

Next, referring to FIG. 9, Embodiment 4 will be described mainly onfeatures different from Embodiment 1. FIG. 9 is a perspective view ofinner box 35 as viewed from a rear surface side and below inner box 35.FIG. 9 illustrates heat insulating board 51 and straight pipe sectionrestricting members 54 before they are assembled to refrigerationapparatus 1. Straight pipe section restricting members 54 afterassembled are also illustrated in FIG. 9 while being indicated by brokenlines.

Evaporator pipe 38 includes multiple straight pipe sections 383(constituting part of first evaporator pipe 618 and part of secondevaporator pipe 628) that are provided parallel to one another and areequally spaced apart from one another on rear surface 353 of inner box35. In refrigeration apparatus 1 according to this embodiment, intervalsat which straight pipe sections 383 are disposed at an upper part of therear surface of inner box 35 are narrower than intervals at whichstraight pipe sections 383 are disposed at a lower part of the rearsurface of inner box 35. In multiple straight pipe sections 383, twoopposite straight pipe sections 384, which lie opposite to each othervia first cascade condenser 616, second cascade condenser 626 and heatinsulating board 51, are disposed between inner box 35 and first andsecond cascade condensers 616, 626, which are not illustrated, that is,between inner box 35 and heat insulating board 51.

Refrigeration apparatus 1 of this embodiment includes three straightpipe section restricting members 54 configured to restrict the positionsof straight pipe sections 383. Straight pipe section restricting members54 are rectangular plate-like members, when seen from the front, havingthe same dimensions, and a thickness of straight pipe sectionrestricting members 54 is almost equal to an outer diameter of straightpipe section 383 and is, for example, 10 mm. Straight pipe sectionrestricting members 54 have sufficient rigidity to restrict thepositions of straight pipe sections 383.

In refrigeration apparatus 1 according to this embodiment, straight pipesection restricting members 54 are tiled between straight pipe sections383 so as to be isolated by straight pipe sections 383 and are thenfixed in predetermined positions on rear surface 353 of inner box 35with, for example, adhesive tapes or the like. Thus, straight pipesections 383 can easily be disposed at equal intervals relative to oneanother in the predetermined positions. Consequently, an interior ofcooling compartment 32, not illustrated, can be cooled uniformly. Thenumber of straight pipe section restricting members 54 is not, needlessto say, limited to three.

A member that makes up straight pipe section restricting member 54 ispreferably made up of a heat insulating body that can reduce a heattransmission between inner box 35, that is, cooling compartment 32 andfirst and second cascade condensers 616 and 626 such as a member havingthe same structure as heat insulating board 51. With straight pipesection restricting member 54 configured in that way, the heattransmission between cooling compartment 32 constituting a coolingtarget and first and second cascade condensers 616 and 626 can bereduced to thereby enhance the performance of refrigeration apparatus 1.

In this embodiment, heat insulating board 51 is disposed so as to coveropposite straight pipe sections 384 and straight pipe sectionrestricting members 54.

FIG. 10 illustrates a modified example of heat insulating board 51provided on refrigeration apparatus 1 according to this embodiment. Heatinsulating board 51 illustrated in FIG. 10 includes three projectingsections 55. In other words, heat insulating board 51 includes twogrooves 56. Projecting sections 55 function as straight pipe sectionrestricting members. That is, projecting sections 55 project from heatinsulating board 51 to between straight pipe sections 383 illustrated inFIG. 9 to restrict the positions of adjacent straight pipe sections 383.In other words, opposite straight pipe sections 384 are inserted intogrooves 56, whereby the positions of straight pipe sections 383including opposite straight pipe sections 384 are restricted. Thus,according to this heat insulating board 51, straight pipe sections 383can be restricted to stay in the predetermined positions to thereby coolcooling compartment 32, not illustrated, uniformly. Additionally,according to this heat insulating board 51, compared with the case wherestraight pipe section restricting members 54 are tiled, a gap definedbetween grooves 56 of heat insulating board 51 and straight pipesections 383 becomes smaller. This can reduce the heat transmissionbetween cooling compartment 32, which constitutes a cooling target, andfirst and second cascade condensers 616 and 626 to thereby furtherenhance the performance of refrigeration apparatus 1. Moreover, whencompared with the case where straight pipe section restricting members54 and heat insulating board 51 are configured as separate bodies asillustrated in FIG. 9, since this heat insulating board 51 is the singlemember, heat insulating board 51 provides an advantage that the placingwork can be performed easily and simply.

Heat insulating board 51 may be a member in which a plate-like memberlike a cushion material that easily deforms so as to match the shape ofstraight pipe sections 383 when pressed against straight pipe sections383 is laminated on a plate-like member having a rigidity.

Needless to say, the refrigeration apparatus according to the presentinvention is not limited to the embodiments that have been describedabove and hence can be altered or modified variously. For example, anytwo or more in second heat insulating board 52, third heat insulatingboard 53 and straight pipe section restricting member 54 may be used inparallel in the refrigeration apparatus.

The details of the disclosure of the specification, claims, drawings andabstract that are included in Japanese Patent Application No.2017-101960 filed on May 23, 2017 are incorporated herein by referencein its entirety.

INDUSTRIAL APPLICABILITY

According to the present invention, the refrigeration apparatus can beprovided in which the heat transmission between the cascade condensersand the evaporator can be reduced. Thus, the industrial applicabilitythereof is great.

REFERENCE SIGNS LIST

-   1 Refrigeration apparatus-   2 Machine installing section-   3 Main body-   31 Lid-   32 Cooling compartment-   33 Hinge-   34 Door-   35 Inner box-   351 Lower surface-   352 Right surface-   353 Rear surface-   36 Outer box-   361 Hole-   37 Heat insulating material-   371 Non-packed portion-   372 Insufficiently packed portion-   373 Crack-   38 Evaporator pipe-   383 Straight pipe section-   384 Opposite straight pipe section-   39 Cascade condenser disposition section-   51 Heat insulating board-   52 Second heat insulating board-   53 Third heat insulating board-   54 Straight pipe section restricting member-   55 Projecting section-   56 Groove-   60 Refrigeration circuit-   610 First refrigeration circuit-   611 First compressor-   611 a First oil cooler-   611 b first annular piping-   612 First pre-condenser-   613 First condenser-   614 First separator-   615 First auxiliary decompression device-   616 First cascade condenser-   616 a First outer pipe-   616 b First inner pipe-   617 First decompression device-   618 First evaporator pipe-   618 a First evaporator pipe inlet-   618 b First evaporator pipe outlet-   619 First common fan-   620 Second refrigeration circuit-   621 Second compressor-   621 a Second oil cooler-   621 b Second annular piping-   622 Second pre-condenser-   623 Second condenser-   624 Second separator-   625 Second auxiliary decompression device-   626 Second cascade condenser-   626 a Second outer pipe-   626 b Second inner pipe-   627 Second decompression device-   628 Second evaporator pipe-   628 a Second evaporator pipe inlet-   628 b Second evaporator pipe outlet-   629 Second common fan-   71 Film sheet-   72 Jig

The invention claimed is:
 1. A refrigeration apparatus, comprising: anevaporator that makes up a refrigeration circuit; a first cascadecondenser that makes up the refrigeration circuit; a heat insulatingboard disposed between the evaporator and the first cascade condenser;and a heat insulating material disposed around the heat insulating boardand packed in spaces on upper, lower, left and right sides of the heatinsulating board, wherein the heat insulating material is in contactwith the heat insulating board.
 2. The refrigeration apparatus accordingto claim 1, further comprising a second heat insulating board disposedin a position where the second heat insulating board holds the firstcascade condenser together with the heat insulating board in between. 3.The refrigeration apparatus according to claim 1, further comprising asecond cascade condenser.
 4. The refrigeration apparatus according toclaim 3, further comprising a third heat insulating board disposedbetween the first cascade condenser and the second cascade condenser. 5.The refrigeration apparatus according to claim 1, wherein the evaporatoris an evaporator comprising a plurality of straight pipe sections whichare parallel to each other, and the refrigeration apparatus furthercomprises a straight pipe section restricting member disposed betweenthe straight pipe sections.
 6. The refrigeration apparatus according toclaim 5, wherein the straight pipe section restricting member is a heatinsulating member.
 7. The refrigeration apparatus according to claim 5,wherein the straight pipe section restricting member is a projectingsection that projects between the straight pipe sections from the heatinsulating board.
 8. The refrigeration apparatus according to claim 1,wherein the heat insulating material is packed fully in the spaceswithout any gap left.